This is one of the most common questions I get. We need to stop obsessing about protein and start looking at our consumption of complex carbohydrates. What people should be worried about is cancer, heart disease, diabetes and obesity. These diseases of affluence and poverty are prevalent but starving from lack of protein doesn’t happen much in the united states. Humans need about 10 % of the calories we consume to be from protein. Beans, nuts, seeds, lentils, and whole grains are packed with protein. So are all vegetables as a caloric percentage, though they don’t have enough calories to sustain most people as a principal source of sustenance. These protein sources contain plenty of fiber and complex carbohydrates, where meat contains none.
According to Dr. Dean Ornish, “high-protein foods, particularly excessive animal protein, dramatically increase the risk of breast cancer, prostate cancer, heart disease, and many other illnesses. In the short run, they may also cause kidney problems, loss of calcium in the bones, and an unhealthy metabolic state called ketosis in many people.”
According the the Physician’s Committee Of Responsible Medicine, there are many health problems associated with too much protein intake.
Osteoporosis. High protein intake is known to encourage urinary calcium losses and has been shown to increase risk of fracture in research studies.6,7 Plant-based diets, which provide adequate protein, can help protect against osteoporosis. Calcium-rich plant foods include leafy green vegetables, beans, and some nuts and seeds as well as fortified fruit juices, cereals, and non-dairy milks.
Cancer.Although fat is the dietary substance most often singled out for increasing one’s risk for cancer, animal protein also plays a role. Specifically, certain proteins present in meat, fish, and poultry, cooked at high temperatures, especially grilling and frying, have been found to produce compounds called heterocyclic amines. These substances have been linked to various cancers including those of the colon and breast.8-10
Long-term high intake of meat, particularly red meat, is associated with significantly increased risk of colorectal cancer. The 1997 report of the World Cancer Research Fund and American Institute for Cancer Research, Food, Nutrition, and the Prevention of Cancer, reported that, based on available evidence, diets high in red meat were considered probable contributors to colorectal cancer risk. In addition, high-protein diets are typically low in dietary fiber. Fiber appears to be protective against cancer.3 A diet rich in whole grains, fruits, and vegetables is important in decreasing cancer risk,3 not to mention adding more healthful sources of protein in the diet.
Impaired Kidney Function.When people eat too much protein, it releases nitrogen into the blood or is digested and metabolized. This places a strain on the kidneys, which must expel the waste through the urine. High-protein diets are associated with reduced kidney function. Over time, individuals who consume very large amounts of protein, particularly animal protein, risk permanent loss of kidney function. Harvard researchers reported recently that high-protein diets were associated with a significant decline in kidney function, based on observations in 1,624 women participating in the Nurses’ Health Study. The good news is that the damage was found only in those who already had reduced kidney function at the study’s outset. The bad news is that as many as one in four adults in the United States may already have reduced kidney function, suggesting that most people who have renal problems are unaware of that fact and do not realize that high-protein diets may put them at risk for further deterioration. The kidney-damaging effect was seen only with animal protein. Plant protein had no harmful effect.11
The American Academy of Family Physicians notes that high animal protein intake is largely responsible for the high prevalence of kidney stones in the United States and other developed countries and recommends protein restriction for the prevention of recurrent kidney stones.12
Heart Disease. Typical high-protein diets are extremely high in dietary cholesterol and saturated fat. The effect of such diets on blood cholesterol levels is a matter of ongoing research. However, such diets pose additional risks to the heart, including increased risk for heart problems immediately following a meal. Evidence indicates that meals high in saturated fat adversely affect the compliance of arteries, increasing the risk of heart attacks.13 Adequate protein can be consumed through a variety of plant products that are cholesterol-free and contain only small amounts of fat.
Weight Loss Sabotage. Many individuals see almost immediate weight loss as a result of following a high-protein diet. In fact, the weight loss is not a result of consuming more protein, but by simply consuming fewer calories. Over the long run, consumption of this type of diet is not practical as it can result in the aforementioned health problems. As with any temporary diet, weight gain is often seen when previous eating habits are resumed. To achieve permanent weight loss while promoting optimal health, the best strategy involves lifestyle changes including a low-fat diet of grains, legumes, fruits, and vegetables combined with regular physical activity.
The cancer connection is spelled out at length in a fantastic book by Cornell scientist T. Colin Campbell, called The China Study. Basically, there is overwhelming scientific evidence to implicate that animal protein consumption causes cancer.
Here are just some examples of healthy protein sources.
Healthy Protein Sources (in grams)
|Black beans, boiled (1 cup)||15.2|
|Broccoli (1 cup)||4.6|
|Bulgur, cooked (1 cup)||5.6|
|Chickpeas, boiled (1 cup)||14.5|
|Lentils, boiled (1 cup)||17.9|
|Peanut butter (2 tbsp)||8.0|
|Quinoa, cooked (1 cup)||11.0|
|Seitan* (4 oz)||24.0|
|Spinach, boiled (1 cup)||5.4|
|Tempeh (1/2 cup)||15.7|
|Tofu, firm (1/2 cup)||19.9|
|Whole wheat bread (1 slice)||2.7|
“Be the change you want to see in the world.” Gandhi